One approach to avoiding the minority carrier transport time limitation has been to build devices that rely on carrier flow using the mechanism of resonant quantum mechanical transmission through multiple barriers.
Resonant quantum mechanical transmission has been reported in Applied Physics Letters 24, 12, 15 June 1974, as a physical mechanism that could be employed to produce a particularly high speed type of device. One type of structure employing this physical mechanism is shown in copending application Ser. No. 280,141, filed June 30, 1981, now abandoned; also identified as European Patent Publication No. 0068064 05/01/83, in which a device has three contiguous layer regions of the same conductivity type semiconductor material with two identical barriers between the external layers and the internal layer.